(1) Field of the Invention
The present invention relates to a flow measurement device and, more particularly to a flow measurement device preferably used in technical fields for supplying a small amount of oil and feeding particulates and the like.
(2) Description of the Related Art
Recently, it is required to realize dry cutting works and to optimize of lubricating for bearings. In these applications, flow rates of lubricating oils are only a few several mL/h [milliliter per hour] and very small, methods to feed multi phase flows made by atomization and intermittent dropping of the lubricating oils are applied because feeding the lubricating oils by saturated consecutive flow is difficult. On the other hand, a method for in-line measuring the flow rate in oil-air method that is mainstream in a technical field of a very small amount of oil feeding, have not been provided because of a specificity of flow state of the oil-air method. Therefore, feeding the oil-air cannot help depending on a movement frequency of volumetric pump. The movement frequency is measured by electric or air timer in present situation. Meanwhile, reliable measurement method for measuring a flow rate of the very small amount of oil feeding described above have not been established. Further, in this technical field, a stability of an injection amount from the volumetric pump is about 20%, because the injection amount from the volumetric pump is very small and not stable.
Reflecting such a situation, a very small particulate flow measurement device using micro wave is suggested in Japan Patent No. 2573645. In Japan Patent No. 2573645, a sift of an interference pattern is detected by irradiating micro wave beam to flow passage of the minim particulate penetrating a cavity filled with a dielectric substance and the minim particulate flow rate is analyzed based on the sift of the interference pattern.
However, it is a problem that a measurement result is influenced by a position (physical location) of a particulate within the flow passage because constant potential of the micro wave cannot be provided in a cross sectional direction of the flow passage (a direction perpendicular to a longitudinal axial direction of the flow passage).